I was in my backyard stargazing. It was a clear night and from the East I saw 4 lights streaking across the sky moving in close proximity to one another. The lights had an orange tinge to them. The altitude appeared to be well below that of satellite orbits. The lights disappeared in the sky to the West of me. They were travelling at a high rate of speed and were only visible to me for about 5 seconds. No sound.Stealth aircraft training in our area?